Osiris, just because you don't like a system doesn't mean you should spout bull **** about it.
Tai chi is like any other art, including Bjj in that if improperly trained no it's not effective, but if properly trained a practitioner is more lickly to win.
And if you did research, Which we know you don't (look no furthur than the Maya Capoiera thread) you wouldn't sound so stupid.

the world you live in is just a sugar coated toping. beneath it is another world. The real world. and to survive there you must learn to pull the trigger!!!-Blade

Lack of video is *the* problem. Without it, nobody will believe the stories masters (and students) tell, even if they're true. My master claims to have won numerous streetfights with some token IMA, including Taiji. I believe him, because I have seen and felt his internal power and fighting skills on many occasions. But that won't convince people like Osiris. Which is just healthy skepticism, I suppose. But don't forget that the 99% sux-rate in CMA means that 1 out of every 100 practitioners can still fight ;)

For more familiar ground, Shooter and his students are known to do well in NHB with Taiji. Whether they "really" do Taiji was a matter of inquiry some time ago...

That being said: what 99% of people learn is Taiji taught as exercise or performance. Given that Chinese martial arts *taught as martial arts* already have a high sux-rate, it's vastly higher for "Taiji" when that includes all the people who think they practice it but don't even *know* it's MA.